A conventional reciprocating pump comprises a rotating crankshaft pivotally attached to a connecting rod, which is in turn pivotally connected to a pump component such as a plunger, a piston or a diaphragm, to convert rotational movement of the crankshaft to linear reciprocating movement of the pump component. Such conventional pumps, however, may be expensive and time consuming to produce, repair and maintain due to the number and complexity of mechanical parts, and the potential need to disassemble the entire pump even if damage is isolated to a particular part.
United States Patent Application Publication No. 2011/0286867 A1 to Lesko discloses a mud pump that includes a frame, a pump module, a pump shaft having an eccentric lobe, a slide movable linearly side-to-side within the frame, a connecting rod having a first end on the eccentric lobe and a second end rotatably pinned to the slide, and a piston rod assembly coupling the slide to the pump module. Rotation of the pump shaft causes the slide to move side-to-side within the frame, which in turn causes the piston rod assembly to operate the pump module in a side-to-side motion.
United States Patent Application Publication No. 2012/0097025 A1 to Fritsch discloses a drive mechanism for oscillating positive-displacement machines such as a diaphragm pump. The drive mechanism comprises an eccentric shaft and a plurality of piston rods. The piston rods are connected to the eccentric shaft by way of a sliding unit guide so that rotation of the eccentric shaft produces an oscillating linear movement of the piston rods.
There remains a need in the art for a drive mechanism that converts rotating motion of a drive shaft to reciprocating motion of a reciprocating pump component that can be used in various types of reciprocating pumps. Preferably, such a drive mechanism is economical and convenient to manufacture, operate and service, and allows for desirable pump characteristics such as a compact layout, reduced internal friction and smooth discharge of the working fluid, while maintaining adequate pump capacity and power.